Let’s break it down a little bit more.There are three basic Japanese sentence structures and the most important part comes at the end.①(noun)は(noun)②(noun)は(adjective)③(noun)は(verb(intransitive))／(noun)は(object)を(verb(transitive))The end of the example sentence is “歓迎(する)= to welcome”, so it is ③.
Make it this long example sentence basic.

(person)は(arriving)を(welcome)。Mr. Maehara welcomes arriving.

Others are additional information. We will see it reversal.Underline parts are added at each stage.